Pinard et al. (1995)first used the term
reduced impact logging (RIL) in 1995. They defined RIL as efficient
timber harvesting, which is executed in such a way that damage to the forest
ecosystem is minimized. The first efforts to reduce logging damage in the
tropical rain forest date from the 1950s, when directional felling was
introduced in the Philippines to avoid damage to potential crop trees (Reyes,
1968). In the same period, the first publications on logging damage in Malaysia
appeared (Nicholson, 1958; Wyatt-Smith and Foenander, 1962). This led to the
introduction of pre-felling climber cutting in the late 1960s (Fox, 1968).
However, serious efforts to modify the complete logging operation with the dual
aim to reduce damage and to improve efficiency were not undertaken in Southeast
Asia until the late 1970s, and even later in Latin America and Africa.

The first true RIL system for tropical rain forests was
developed in the late 1970s in Sarawak, Malaysia (Mattson-Marn and Jonkers,
1981). In the 1980s, other RIL systems were developed in Australia (Ward and
Kanowski, 1985) and in Suriname (Jonkers and Hendrison, 1987; Hendrison, 1990).
In the meantime, concern over continuing deforestation placed the need for
improved management of tropical forests on the international political agenda.
Consequently, RIL research really gained momentum in the 1990s. Many studies
were initiated, for example in Indonesia (Bertault and Sist, 1995), the
Malaysian state of Sabah (Pinard et al., 1995; Cedergren et al.,
1994), Brazil (Johns et al., 1996; Blate, 1997), Guyana (van der Hout and
van Leersum, 1998; van der Hout, 1999; 2000; Armstrong, 2000) and Cameroon (van
der Hout and van Leersum, 1998; Jonkers and van Leersum, 2000; Jonkers, 2000;
Durrieu de Madron et al., 1998). Furthermore, a code of practice was
formulated, which applies worldwide (Dykstra and Heinrich, 1996).

Research results showed that logging damage can be reduced
substantially, and that introducing improved logging techniques could be
financially attractive for logging firms. However, most timber companies are
reluctant to change their operations in spite of the favourable research
findings (Putz et al., 2000a). Furthermore, RIL studies relate mainly to
efficiency and costs, and to damage to vegetation and soil, which do not address
fully the impediments to adoption. During the 1990s, many organizations made
efforts to develop criteria and indicators for sustainable forest management and
many of them are also relevant to logging. It may be that current RIL methods
have to be adjusted to meet the requirements of sustainable forest
management.

In this paper, four cases are discussed in which the author
was involved directly: the RIL methods developed in Sarawak in the 1970s, in
Suriname in the 1980s and in Guyana and Cameroon in the 1990s. This paper
explains how and why these approaches differ from one another and what steps
should be taken to improve them further as well as other methods. The methods
are described briefly. For more complete descriptions, the references at the end
of each case study can be consulted.

CASE STUDIES

Case 1: Sarawak

The site

The Sarawak method was tested in a dipterocarp forest on
undulating terrain, in a logging concession approximately halfway between the
towns of Miri and Bintulu. The dipterocarp forests in Sarawak are generally
richer in commercial timber than forests in Africa and South America, although
the yield in this particular experiment was rather low by Malaysian standards of
the 1970s. About 14 trees/ha were harvested, yielding about 54 m3/ha.
Large commercial timber trees were scattered over the whole experimental site
without an obvious spatial pattern, although there may have been a slight
tendency to clumping. Before logging operations started, the area was
uninhabited; the opening up of the area soon attracted a small number of
settlers.

The method

Designing an improved logging method was one of the activities
of a project implemented by the Food and Agriculture Organization of the United
Nations (FAO). The project also dealt with silviculture, forest management and
timber processing. Mattson-Marn, the projects logging expert, had come to
Sarawak to design a logging system which was less costly and more efficient than
the existing methods, but reducing logging damage was not explicitly part of his
terms of reference. Nonetheless, his method contained most elements used in more
recent RIL methods:

For felling and
skidding, the same machines were used as in conventional logging. The method was
based on improved working methods rather than on technical
innovations.

Logging started with mapping
of terrain conditions and of trees to be harvested.

The maps were used to align
the main skid trails, which were 100-150 m apart, at right angles to the logging
road and as straight as possible. These trails were as close as possible to
concentrations of trees to be felled and steep grades were avoided. The main
trails were opened prior to felling.

Trees were felled usually at
angles of 30°-40° to the skidding direction (a herring-bone
pattern) to facilitate skidding. For the same reason, often trees were
felled into existing felling gaps, natural openings or tracts of open forest,
which reduced the amount of logging debris and therefore resulted in fewer
obstacles. Improvements in felling techniques also included safety features and
measures to reduce logging residues.

Log extraction was done with
choker cables that allow hauling of two or more logs at the same time.

Secondary trails were made as
skidding progressed to reach logs that could not be skidded directly from the
main trail. Winching was not prescribed explicitly, and was seldom used for
distances over 6 m.

Efforts focused on activities within the logging compartments
and improvements in planning, and construction of roads and truck transport were
not investigated.

The results

As a result of this planned way of working, logging costs per
cubic meter extracted were reduced by 23 percent, which is due partially to
lower skidding costs and partially because less timber had been wasted. Although
the method had not been designed to reduce logging damage, the number of trees
destroyed by logging had almost been halved.

Reference: Mattson-Marn and Jonkers, 1981.

Case 2: Suriname

The site

Suriname is a small country in South America. The Celos
Harvesting System developed by Hendrison (1990) was meant for the Forestry
Belt, a 40 to 120 km wide and 400 km long zone in the northern part of the
country. The terrain is flat to undulating. The forest contains fewer timber
trees than the Sarawak forest, and these trees are considerably smaller. Some
5-8 trees/ha are harvested, seldom yielding more than 20 m3/ha. The
spatial distribution of commercial timber trees is usually random. The Forestry
Belt is virtually uninhabited by humans.

The method

The Celos method was similar to the one developed in Sarawak,
with the following modifications in felling and skidding:

Felling was
directional, but as the number of trees to be felled per hectare was
considerably less than in Sarawak, there was no need to adhere strictly to a
herring-bone pattern. Trees could be felled in any direction, as long as the
angle with the main skid trail was approximately 40°, not less than
10° and not more than 60°. As there were hardly any clumps of timber
trees to be spared, the objective of directional felling was to facilitate
skidding and not to preserve potential crop trees. When necessary, wedges were
used to direct the tree in an appropriate direction.

Given the low yield per
hectare, fewer landings were required. In Sarawak, one landing was constructed
per main skid trail or per two trails, while in Suriname, one landing per three
to six main trails was sufficient. This led to a dendritic skid trail
pattern.

Winching was prescribed. In
principle, the skidders were instructed not to leave the main trails and logs
were to be winched to the trails whenever possible. Choker cables were not
used.

Frequently, used skid trails
were considered as a part of the permanent infrastructure. Soil mechanical
studies had shown that using a trail for more than two loads led to such severe
compaction that regeneration was impossible for at least several decades. The
method was tested in a forest that had been logged in the early 1960s, and many
old trails were still without woody
vegetation[26]. These trails were re-used
whenever possible and were therefore mapped during the pre-harvest survey. Also,
the trail network was planned in such a way that branch trails were used for not
more than two loads.

The results

The results were comparable to those obtained in Sarawak:
additional expenditures for surveys, planning and pre-harvesting operations
added about 5 percent to the logging costs. This increase was more than
compensated for by reduced skidding costs and improved efficiency. The Celos
method also significantly reduced logging damage. The area under skid trails was
reduced by about 50 percent to a mere 5 percent of the total area.

References: Jonkers and Hendrison, 1987; Hendrison,
1990.

Case 3: Guyana

The site

Forests in Guyana are, as in neighbouring Suriname, relatively
poor in timber trees and log dimensions are rather small, usually less than 70
cm in diameter. Traditionally, logging has targeted mono-dominant groves of
exploitable species in the forest, the most important being greenheart
(Chlorocardium rodiei). Recently, the range of commercial species has
been broadened by an increased demand for peeler species.

Several RIL studies have been conducted in Guyana, but only
the activity at the Tropenbos site near Mabura Hill is discussed here. Logging
in this concession, although influenced by an increased marketability of
lesser-used species, still focuses on greenheart. Because this species is
limited to certain parts of the forest, selective logging is disturbing the
landscape in a patchy fashion. Although the average yield is not higher than in
Suriname, exploitation locally can reach 20 stems/ha or 60 m3/ha. The
terrain in the study area is almost flat. Like most forested regions in Guyana,
the area is almost uninhabited by humans. The population of the only settlement
nearby, Mabura Hill, consists almost entirely of the personnel of the timber
company and their families.

The method

Logging was confined to those parts of the forest where
greenheart was present. The method was adapted from the one developed by
Hendrison (1990) in Suriname. The most important modifications were:

Lianas were cut
six months prior to felling.

Some selection criteria for
trees to be felled were introduced, that is, diameter limits for individual
species were set at 20-30 cm below the maximum diameter the concerned species
could reach without developing decay. These limits were higher than required by
law.

During directional felling,
the herring-bone pattern was adhered to more strictly.

Skid trails were marked in the
field prior to logging, but opened up only shortly before skidding.

The reason for the last two adaptations of Hendrisons
method was the high local logging intensity. In Suriname, there was usually
ample space for the skidder to manoeuvre in case a tree had been felled in the
wrong direction or in case of other unforeseen obstacles. In Guyana, however,
much more timber and logging debris remains on the forest floor after felling,
thus reducing the manoeuvring space of the skidder. Felling trees in the same
direction and allowing the skidder operator to adjust the course of a trail if
necessary allows operators to avoid obstacles.

The results

Again, RIL reduced the area under skid trails by about 50
percent. The number of trees damaged by skidding was reduced by the same
percentage. Felling damage was not reduced, however, and may even be more severe
than in conventional operations if felling intensity is high. This is because in
conventional logging, trees are more likely to be felled into existing felling
gaps, thus creating less damage but larger canopy openings. Research had shown
that such multiple tree gaps are not favourable for regeneration of commercial
species; nevertheless, they were preferred to avoid large gaps.

The costs per cubic meter extracted under RIL were slightly
less than under conventional logging. The difference would have been more
substantial if the same felling limits had been applied in both
methods.

Two RIL studies have been conducted in Cameroon, but only the
Tropenbos study is discussed here. The Tropenbos site is located in the
southwest of the country. The physiography is undulating in parts, but more
often hilly or mountainous and highly dissected. An important difference from
the other three cases is that people reside in the area. They practice shifting
cultivation, hunt and gather non-timber forest products. Population density is
about 7 persons/km2. Easily accessible parts are used mostly for
shifting cultivation, and logging has to be practised mainly in difficult
terrain. The forest differs in many respects from the forests in Sarawak,
Suriname and Guyana. The high number of tall emergent trees with trunk diameters
of 1 to 2.5 meters or more (about 7/ha in the logging experiments) is
remarkable. Only a few of these giants belong to marketable species, and the
average logging intensity is well below one tree/ha. Only very large trees are
cut, and the average volume extracted is about 10 m3/ha. As in
Guyana, the bulk of the production comes from one species, in this case
azobé (Lophira alata). Large azobé trees as well as some
other timber species tend to clump, but seldom stand close together. Felling
tends to be concentrated in such clumps, and substantial parts of the forest are
not affected by felling.

The method

The RIL method developed by the Tropenbos-Cameroon Programme
is again based on the method of Hendrison (1990) described above. The following
adjustments were made:

Directional
felling was prescribed, but with another objective. Whenever possible, the trees
were directed away from potential crop trees visible from the stump and into an
existing (felling) gap or a patch of young forest. The felling directions were
determined during the inventory, and marked both on the trees and on the survey
map. Wedges were not used.

Pre-felling skid trail
alignment was applied, aimed at minimizing skidding distances and the area under
trails. The trail pattern was influenced strongly by terrain conditions and the
spatial distribution of trees to be felled. The main trails were generally 100 m
or more apart, in as straight lines as possible and passed concentrations of
felled trees within winching distance. Branch trails were constructed only where
isolated felled trees could not be reached from the main trail. The trail
alignment was such that the predetermined felling directions made angles of
approximately 40° with the trails. Thus, the skid trail alignment was
attuned to the felling directions, and not the other way around, as in
Suriname.

The first adjustment was made because medium-sized and small
trees of commercial species are relatively scarce and often occur in groups.
This makes it highly desirable and feasible to reduce the damage caused by
falling stems. Furthermore, it is less critical to pay special attention to
avoiding large gaps. Under the prevailing harvest intensity, multiple tree gaps
are rare and some timber species regenerate poorly in small gaps. This does not
apply to most timber species, however, and preferably, felling should not lead
to gaps exceeding 1 300 m2.

The results

At the onset of the project, there was doubt if directional
felling and winching would be feasible, given the large tree sizes and the heavy
weights of the logs. However, it appeared that winching over distances up to 20
m was applied already in conventional logging to recover logs on steep slopes.
Furthermore, the experienced felling instructors could direct virtually all
trees to be felled in any direction within 90° of the trees natural
lean. Although the local fellers were less successful than their trainers in
this respect, felling damage to trees of commercial species could be reduced by
more than 40 percent.

In conventional logging, the area under skid trails was only
4.3 percent. With RIL just a modest reduction to 3.9 percent could be realized.
More important is that after RIL skidding, part of the vegetation had survived
on 47 percent of the trail length, compared to 29 percent after conventional
logging. These parts of the trail network had been used for the extraction of
one or two felled stems only, and are likely to recover more rapidly than other
sections because some vegetation remained and because the soil had been less
compacted.

A difference in costs between RIL and conventional logging
could not be demonstrated, although the RIL method is probably somewhat less
expensive.

All four methods discussed lead to reductions in damage to
vegetation and soil, higher recovery of usable timber and safer working
conditions. Furthermore, they do not require major investments. The RIL methods
discussed are remarkably similar. Differences in approach relate mainly to
differences in logging intensity and forest composition. This probably applies
also for most other RIL methods.

Some issues, like incentives for logging operators to
stimulate them to produce quality work, still need to be resolved. Otherwise,
the methods are ready to be implemented by the logging companies. Further
technical refinements are certainly possible. For instance, use of the global
positioning system (GPS) can improve the accuracy of mapping and planning. These
are not the most important issues for the near future, however. Two crucial
questions remain:

There are many explanations for the reluctance of the timber
industry to accept RIL (Putz et al., 2000a), but none apply to all
companies. Some relate to constraints in introducing new methods. Change always
brings unexpected problems and costs, which may outweigh financial gains in the
short term. Furthermore, improvements in mapping and planning mean extra office
work and more coordination, supervision and communication, and therefore a
change in the logging companys organization, which may be quite
fundamental.

Many timber companies also doubt the profitability of RIL
after the introduction period. When improved logging techniques are combined
with other measures to achieve sustainable forest management, RIL may indeed be
more expensive (see Tay et al., this volume). Examples of such measures
are the application of higher felling limits or restricting logging in parts of
an area for environmental and other reasons. Introducing such elements may be
good forest management, but may lead to higher costs. Applying RIL without such
additional prescriptions will generally be less costly than conventional
logging.

Another explanation is that conventional logging has at least
one important advantage for timber companies in comparison to RIL. The prime
objective of timber companies is to maximize profits from timber processing and
timber sales. Hence, they want to be able to respond flexibly to changes in
timber prices and orders from buyers. Timber prices fluctuate considerably and
unpredictably. It is therefore difficult to predict if logs of lesser quality
can be sold or processed profitably. This applies also to good-quality logs of
tree species that yield low-priced timber or are less in demand. In conventional
logging, timber companies respond to poor market conditions by leaving trees for
which there is no demand uncut, and return later, when market conditions have
improved, to the same tract of forest to harvest the remaining timber. This
flexibility is not foreseen in RIL. An assumption of RIL is rather that all
timber is removed in one single logging operation, as re-entry always causes
extra damage and costs. One may of course consider allowing re-entry under
specified conditions, but it would be better if the problem could be resolved
through better marketing, long-term sales contracts and other market-oriented
strategies.

Aspects of sustainable management

Sustainable rain forest management has to meet many
ecological, social, economic and technical criteria. As RIL is supposed to
contribute to sustainable forest management, it is logical that RIL has to
comply with these standards also. RIL research has focused so far on efficiency
and reduction of damage to vegetation and soil. In addition, safety aspects and
the impact of gap size on regeneration of timber trees have been taken into
consideration. Some important aspects, which have received little attention so
far, are discussed below.

Impacts on wildlife

There are many studies on ecological impacts of logging, such
as consequences for floral and faunal biodiversity, but these studies were
seldom in relation to RIL (Putz et al., 2000b). Although it is likely
that RILs impact on biodiversity is lower than conventional logging, the
impact on fauna requires more attention. Logging affects fauna indirectly
through hunting (Bennett and Robinson, 2000), because it opens up the forest for
hunters and because of hunting by logging personnel. Direct impacts include
damage to vegetation (changes in microclimate and availability of food plants)
and habitat disturbance caused by the mere presence of logging personnel and the
noise of machinery. The last aspect, which affects especially the larger
mammals, is documented poorly. At the Tropenbos site in Cameroon, Bagyeli
pygmies and other hunters complain that larger game is chased away by the noise
of logging operations, and that it takes many years for populations to recover
(van den Berg and Biesbrouck, 2000), which is supported by other, yet
unpublished evidence (van Dijk, pers. comm.; Tovar, pers. comm.). In fragmented
forest areas surrounded by shifting cultivation, game may even disappear
forever.

RIL does not reduce hunting pressure, but it diminishes damage
to vegetation and it also reduces the duration of the entire logging operation.
The impact on fauna should be reduced further by preventing logging operations
from being executed concurrently over large continuous areas, that is, by
ensuring that the animals have a place to where they can flee and from where
they can return after logging has been completed.

Social impacts

Social impacts have been neglected in RIL research. Where
logging operations are in uninhabited areas this is justified, as the only
social function of logging is providing employment. However, most logging
companies have to deal with local people, who also use the forest, inter
alia, for hunting and gathering of non-timber forest products. Logging
interferes with the lives of villagers in both positive and negative ways.
Logging roads make it easier for them to trade and travel. The company may also
provide some employment and compensation for inconveniences caused by logging.
These benefits are offset by substantial social and direct financial costs.
During the harvesting operations, it is not safe for the villagers to enter a
forest where logging is in progress; thus, their access to forest resources is
reduced. The aforementioned impact on fauna also has social consequences. At the
Tropenbos site in Cameroon, wildlife provides virtually all of the proteins for
the local population (van Dijk, 1999), which means that continuous access to the
forest is vital. This illustrates that social aspects have to become an integral
feature of RIL planning, and that this planning should be discussed with the
people to ensure their interests are taken into account adequately. Logging
should be planned in such a way that individual villages always have access to a
considerable part of the forest. Furthermore, prescriptions for directional
felling may have to be adjusted to preserve treesthat produce non-timber forest
products.

Yield regulation

A basic assumption of sustainable management is that the
amount of timber harvested per year is equivalent to the potential annual volume
increment. This means that the allowable cut should be integrated in RIL
planning. When the methods discussed in the case studies were developed, growth
and mortality data were insufficient to assess the allowable cut with
satisfactory accuracy, although yield prediction models were developed by the
Sarawak and Cameroon projects (Jonkers, 1982; Ebaa, 2000). Reliable data
from growth and yield experiments established in the 1970s in Sarawak and
Suriname now exist, and introducing the allowable cut in the RIL methods
concerned is therefore possible and recommendable. In Sarawak, steps in this
direction have been undertaken already (see also Ago Dagang et al., this
volume). Diameter limits set for trees to be logged should well exceed the size
at which the species flowers for the first time, and be at least 20 cm below the
maximum diameter at which the species starts to develop unacceptable decay, even
if the yield prediction model suggests otherwise.

ACKNOWLEDGEMENTS

This paper is based on results of projects executed by FAO and
the Sarawak Forest Department (Sarawak), Celos (Suriname), Wageningen University
(Suriname, Cameroon), Institut de Recherche Agronomique (IRAD) (Cameroon) and
Utrecht University and the Guyana Forest Department (both Guyana), in
collaboration with their industrial partners. The projects received financial
support from the Tropenbos Foundation (Cameroon, Guyana), the United Nations
Development Programme (Sarawak), the International Tropical Timber Organization
(ITTO) and the Common Fund for Commodities (Cameroon). The author would like to
thank these organizations, and the numerous individuals who contributed to the
success of the projects concerned.